You’ve probably heard the advice: One of the best things you can do to stay healthy, especially as cold and flu season approaches, is to stay physically active.
This lore has been around for a long time, but until recently, researchers didn’t have much data to support the idea. Now, scientists studying risk factors related to COVID-19 have found Preliminary evidence on the association between regular exercise and improved immune protection against disease.
When researchers reviewed 16 studies of people who were physically active during the pandemic, They found that exercising was associated with a lower risk of infection as well as a lower chance of severe COVID-19. The analysis, published last month in the British Journal of Sports Medicine, generated much enthusiasm among exercise scientists, who say the findings could lead to updated guidelines for physical activity and health care policy around exercise.
Experts who study immunology and infectious diseases tend to be more cautious in interpreting the results. But they do agree that exercise can help protect health through several different mechanisms. They found that exercise was associated with a lower risk of infection as well as a lower chance of severe COVID-19. For decades, Scientists have observed that people who are fit and physically active have lower rates of various respiratory tract infections. And when people who exercise do get sick, they tend to have a less severe illness, said David Niemann, a professor of health and exercise science at Appalachian State University who was not involved in the recent Covid-19 review. ,
“The risk of serious outcomes and mortality from the common cold, influenza, pneumonia, they are all significantly reduced,” Dr Niemann said. “I call it the vaccine effect.”
The new meta-analysis that analyzed studies between November 2019 and March 2022 found that the impact extends to COVID-19., Worldwide, people who exercised regularly had a 36% lower risk of hospitalization and a 43% lower risk of death from COVID compared to those who were not active. They also had less chance of contracting Covid.
People who follow guidelines that recommend at least 150 minutes of moderate activity or 75 minutes of vigorous activity per week get the most benefit. But those who exercised less were also more protected from disease than those who did nothing.
Researchers believe that Exercise can help fight infectious bacteria and viruses increased circulation of immune cells in blood, For example. In some smaller studies, researchers also found that muscle contraction and movement release signaling proteins called cytokines, which help immune cells find and fight infection.
Even if your levels of cytokines and immune cells drop two to three hours after you stop exercising, Dr. If you exercise every day, your immune system becomes more receptive and able to take on pathogens faster over time, Niemann said. “Your immune system is better and better positioned to deal with the viral load at any given time,” he said.
In healthy humans, physical activity also Has been linked to less chronic inflammation. Extensive inflammation can be extremely harmful, even turning your own immune cells against those of your body. This is a known risk factor for COVID-19, Dr. Neiman said. So it makes sense that reducing inflammation could improve your chances of fighting infection, he said.
Research also shows that exercise may enhance the benefits of certain vaccines. For example, people who exercised right after receiving the COVID-19 vaccine produced more antibodies. And in a study of older adults who were vaccinated early in flu season, those who exercised had antibodies that lasted all winter.
An infectious disease specialist at the Johns Hopkins University School of Medicine, Dr. Stuart Ray said, exercise offers many broad health benefits that can help reduce the incidence and severity of disease. Jogging, jogging, hitting the gym or adding a sport of your choice to your daily routine is known to help reduce obesity, diabetes and heart disease.For example, these are all risk factors for severe influenza and COVID-19. Exercising can help you get more restful sleep, improve your mood, and improve your insulin metabolism and heart health, improving your chances against the flu and COVID-19. It’s hard to know, Dr. Ray said, whether the benefits come from direct changes in the immune system or simply from better overall health.
Peter Chin-hong, an infectious disease specialist at the University of California, San Francisco, agreed that more research was needed before scientists could pinpoint a specific mechanism or causal link. In the meantime, he said, it is important not to rely too much on it.
“Right now, you can’t say, ‘I’m going to the gym to avoid getting COVID,’” Dr. Chin-hong said. The problem with studying the precise effect of physical activity on immunity is that Exercise is not something that scientists can easily measure on a linear scale Dr Ray said. “People exercise in many different ways.”
Study participants often self-report the amount and intensity of their exercise, which can often be inaccurate., And just expecting exercise to be beneficial can provide a powerful placebo effect. As a result, it can be difficult for researchers to say how much exercise or which type is ideal for immune function. It’s also very possible that people who exercise regularly share other characteristics that help them fight infection, such as a varied diet or better access to health care, Dr. Ray said.
In addition, “there’s a huge debate about whether exercising too much makes you more vulnerable to infection and disease,” said Richard Simpson, who studies exercise physiology and immunology at the University of Arizona. .
Marathon runners often report being sick after a race, Dr. Simpson said, and Some researchers believe that too much vigorous exercise may inadvertently increase cytokines and inflammation in the body. He added that exercising without rest also depletes the body’s glycogen stores, which can lead to impaired immune function for some people for hours or days, depending on their initial health. And exercising in groups or attending intensive sports training camps can expose athletes to more pathogens. Other experts point out that people who are physically active simply want to monitor their health more closely.
Still, for the average athlete, preliminary evidence suggests there may be a protective effect against serious illness. But people who have trouble getting enough exercise or can’t do anything for some reason shouldn’t be discouraged, Dr. Ray said. “What helps one person to be healthier than another is a complex combination of factors.”